We had good luck with the EX-1 and braze ons, but we had a different ex-1 than you linked. You linked the disc version we used:
Blackburn EX-1 Rack - mikesbikes.com We have done a bunch of long tours including coast to coast ones with the EX-1 and carried a variety of different loads. We also did a lot of commuting and errand running. We never found it lacking.

FWIW I used the non disc version on a disk bike using braze ons, but it required a bit of bending and some short spacers on my disc MTB.

I have been using lighter bikes with skinnier tires and an ultra light load and for that use have use one from the Axiom Streamliner line. I have been very happy with it.